Atopic Dermatitis in Pets - Itchy & scratchy
Atopic Dermatitis : Key Points
The clinical signs are chronic and recurrent itching and/or inflammation/infection on any part of the skin, chewing at feet, rubbing face on the ground or with paws becuase it is itchy and ear infections.
It is a genetic condition that cannot be cured - it can only be controlled.
It can be very difficult to control in some dogs and is very frustrating for pets owners and their vets also!
Diagnosis may require blood and skin tests as well as a history of recurrent skin conditions
Treatment involves use of anti-inflammatories, antibiotics, shampoos and other medications.
Treatment can often be for life, with more medications required at certain times of the year.
What is Atopic Dermatitis?
Atopic dermatitis is an inflammatory, chronic skin disease caused by allergies. It can also be termed Allergic Dermatitis or Atopy, and animals that have this condition are termed 'atopic'.
In simple terms it is chronic and recurrent itchy skin and/or ears due to having allergies that trigger itchy and inflammed skin and/or ears. It is a life-long condition that can be controlled but not cured.
Atopic Dermatitis is an itch that responds to anti-inflammatory steroids and that isn’t caused by:
>Anything with legs (fleas, mites)
>Anything that can be grown in a laboratory (bacteria, yeast)
>Anything eaten (food, medications)
The aim of veterinary medicine is to find a medication that will stop the terrible itching and other related symptoms all the time in all pets but have no side effects. A new medication called Apoquel is now available in Ireland. This new treatment is much closer to the ideal than anything we have had up to now and is revolutionising the way we can treat and control atopic dermatitis. In Blacklion Pet Hospital have a lot of experience with this fantastic new medication so if you have an itchy dog please give us a call us to make an appointment so we can see you and try to get your doggy back to being comfortable and happy as soon as possible.
Atopy is a genetic condition - these pets are conceived and born predisposed to being allergic. Some breeds (such as Westies) are much more prone to developing atopy and others (such as Greyhounds) are almost never atopic. That said any pet can be atopic irrespective of breed and many individuals of a predisposed breed (such as Westies) will never develop atopy.
Nothing you did or didn't do to or with your pet caused him/her to be atopic. They were born with the condition and developed symptoms because they were exposed to different allergens (i.e. things they can be allergic to). However - as you will read later - there are things you can do to reduce the severity of the symptoms they suffer from.
These allergic reactions can be brought on by normally harmless substances like grass, pollens, trees, mould spores, house dust mites, and other environmental allergens. These allergens are inhalled or come into contact with the skin and are absorbed and through a complex process involving the immune system set off a reaction resulting in the skin becoming itchy and inflammed. A highly detailed explanation of the process is available here.
Symptoms and Types
Pets normally show first signs of the disease between 9 months and 3 years of age, but it can develop in younger and older dogs also. In many cases atopic dermatitis can be so mild the first year that it does not become clinically apparent before the second or third year. We commonly see pets presenting to us with the first symptoms of atopic dermatitis in their second summer.
Despite the fact dogs are more prone to atopic dermatitis than cats, it does occur in cats also. In particular we see a condition called Seasonal Allergic Dermatitis in cats where they show signs of itching with scabs on their skin only a certain times in the Spring and Summer or early Autumn. Some cats will develop the symptoms at almost the same time each year - this is because they are allergic to something that 'comes out' at that time, such as a particular pollen or grass.
The signs associated with atopic dermatitis consist of itching, scratching, rubbing, and licking of the skin, especially around the face, paws, groin and underarms with associated inflammation of the skin in those areas. The skin can become inflammed, thickened and infected and the hair often thins or falls out in the affected areas. In white dogs you will often see the hair become red or brown (especially on the feet) and the skin in the affected areas can be come darker, especially in the groin and underarms.
Some pets will ever only show symptoms in one part of their body (e.g. ears or feet); others will show them all over their body. Some pets can be very mildly affected (i.e. just a bit more itchy than normal at certain times of the year and perhaps not even requiring treatment); other pets can be very severely affected. Rarely it can get to the point that if the symptoms cannot be controlled and the pet is so uncomfortable and sick that euthanasia may be considered as the only humane option left.
Some breeds are more prone to getting the symptoms in just one location - for example Labradors are very prone to only showing symptoms with their ears, Poodles their feet.
Diagnosing atopy is generally based on clinical signs of skin and/or ear conditions and a history of these signs recurring on several occasions.
it is not possible to say a pet is atopic the very first time it presents with a skin condition - there are many more things that can cause a one-off skin condition in your pet other than atopy. However unless we can find or suspect a specific cause for your pet presenting with a skin condition (such as mange mites, fleas, an under-active thyroid gland or an over active adrenal gland) we will generally warn you that even if we resolve the symptoms it is possible that they will recur - and therefore that atopy is a strong possibility as the underlying cause.
If your pet does get recurrences of skin conditions that fit with certain recognisable patterns, and if we have ruled out infectious causes (such as mites), food allergies (by placing on a special diet for 3 months) and metabolic causes (such as an under-active thyroid), we can in general then make a clinical diagnosis of atopic dermatitis. To help us make this diagnosis we may need to do bloods tests (to rule out other causes of the skin problems) and skin scrapings, swabs and biopsies.
How severely a pet will be affected is variable and cannot be determined when they first show symptoms. Some will go on to be very mildly affected and may even resolve, others may progressively get worse, others can be very severe from the outset. What we can say is that if your pet is not given the correct treatment they will get worse. It's always better to treat the symptoms early and to keep them from going out of control
At some point blood tests to see what your pet is allergic to may be recommended. This can on the one hand help confirm the diagnosis of atopy and on the other hand can tell us what your pet is allergic to. For an example of an allergy test result see here. In this case the pet is allergic to fleas, a dust mite and a storage mite.
The symptoms we see are due to itchy, inflammed and infected skin so treatment involves reducing the itching and inflammation and clearing up any infections that exist.
The allergy itself causes the itching and inflammation. Both the allergic reaction and the trauma from the itching causes damage to the skin surface. When the skin is inflammed and damaged from the itching it becomes infected due to bacteria and yeasts that normally live on the skin without causing a problem getting deep into this inflammed and damaged skin - these are termed 'secondary infections'. These secondary infections cause more itching - often these infections are actually a greater cause of itch that the allergy itself. The itching due to the inflammation and infection causes more damage to the skin causing more infection and inflammation and so they cycle continues. We call this the 'itch-scratch' cycle.
To stop this cycle we have to reduce the inflammation and 'itchiness' and also treat the secondary infections. We do this by using anti-inflammatories, antibiotics, medicated shampoos and occasionally oral anti-yeast medications. In many cases we have to use very long courses of treatment - usually a minimum of 3 weeks but sometimes we can prescribe for several months. In many cases life-long therapy is required, often with low dosages most of the time and increased dosages at certain times when the symptoms 'fare up' acutely. It all really depends on the individual pet and how they respond and the results of lab tests we may run.
We also always ensure that there are no skin parasites involved by using regular treatments for external parasites.
In some milder cases most of the symptomatic itching is due to the secondary infections and in these cases we try to keep the symptoms under control by regular use of medicated shampoos without having to use oral anti-inflammatories or antibiotics. This is the ideal but not always achievable.
When trying to reduce the underlying allergy the best treatment of all is to remove from your pet's environment what your pet is allergic to. For example if it was found that your pet is allergic to dust mites then if you do what you can to reduce exposure to dust mites the symptoms may resolve. However this is not always feasible - you cannot stop your pet from coming into contact with pollens in the summer for example.
Mite avoidance strategies:
Storage mites: If fed dry food, reduce exposure to dust and crumbs (store in air-tight plastic container, wash this out between batches, wipe animal's face with a wet cloth after feeding, keep bowls and feeding areas clean).
House dust mites: Reduce exposure to house dust mites, e.g. by keeping the animal away from areas of highest burden (bedrooms), vacuuming in conjunction with use of anti-mite bedding protectors, perhaps using anti-mite mattress protectors on sofas and other such soft furnishings, using environmental sprays with licensed effect against house dust mite.
Assuming you cannot remove the allergens from your pet's environment (e.g. pollens) the the next best treatment would be to give your pet something that will prevent it from reacting to what they are allergic to. Unfortunately however there is no magic cure for pets - nor is there for humans with this condition. There is nothing we can do to 'cure' your pet - i.e. give them one treatment and they are fixed for life.
So assuming we cannot remove from your pet what they are allergic to and until medicine invents the magic one-off cure the next best that can be done is to use long term medications to reduce the allergic reaction. This is very similar to how humans control hay-fever by taking anti-histamines or control asthma by taking the preventative inhaler.
The best long-term preventative treatment in our experience is a marvelous drug called Apoquel - it works on nearly all dogs (but not all) and carries minimal side-effects. Other commonly used medications to reduce the allergic response in pets are anti-inflammatory corticosteroids (prednisolone), immunosuppressives (cyclosporin), anti-histamines (although they rarely work in pets) and a treatment called hyposensitisation.
In essence all of these medications work at a cellular level by blocking the allergens from causing a release of inflammatory mediators from cells in the skin and immune system. Which one to use - if any - and how much to use depends on the individual pet.
Other than hyposenstisation (more of which below), all of the other medications must usually be given daily or every second day to reduce the reaction and in turn reduce the itching and inflammation. We can also use anti-inflammatory creams and sprays if only small areas of the body are affected. For ears we can use creams that contain an antibiotic, an anti-yeast medication and an anti-inflammatory.
As all of these medications can potentially (but uncommonly) cause some undesirable side effects, particularly if used at higher doses for long periods of time. In general the idea is to use as little of these medications as possible to reduce the symptoms to an acceptable level (the aim is not necessarily to always stop the symptoms completely but rather to get the pet to a point where they are well and comfortable).
Finding the correct dose, or indeed preferably trying to find a way not to use any of the medications that can cause more serious long-term side effects, is part of the skill of being an experienced veterinary surgeon with a special interest in dermatology. Our aim in Blacklion Pet Hospital is to find a way that we do not have to use any of the potentially more harmful medications for long term treatment but unfortunately even if we do try everything else we can sometimes be left with no option but to use these to relieve your pets symptoms.
Hyposensitisation therapy works differently from the medications above. Very simply a bespoke 'vaccine' is made up for your pet against what they are allergic to (as determined by allergy testing). The 'vaccine' is then given to your pet by injection once monthly for life and the hope is that they will stop being allergic to what they are vaccinated against. For example in the pet with these allergy results we order treatment that works for the 3 things he is allergic to - flea saliva, Dermatophagoides farinae (house dust mite) and Acarus siro (storage mite).
This method has the great advantage of almost always having no side effects but it has a disadvantage of only getting a complete cure in about 1/3 of pets - and only for as long as the vaccine is given every month. Another 1/3 will show improvement but will still have some, milder, symptoms and a final 1/3 will show no improvement at all. Even in the pets that show a complete cure it may approximately take six months to a year to see an improvement. For pets that show no improvement after 12 months the treatment is stopped. We only advise this treatment for pets that need long term therapy. Some pets will get flare ups once or twice a year and our opinion is that is is better to just treat these flare ups as they happen rather than use year round treatment.
Finally we often place pets on special foods that help reduce the symptoms (such as Hills Derm Defence). We also sometimes perform food trials on pets with chronic skin problems to see can we identify if it is a food which is causing a problem. This is a fairly complex procedure that can only be properly done under direction of a vet but that said in some instances an owner may have done some trial and error work themselves and found that some foods cause the problem and their pet is doing well on other foods.
Diagnosing, treating and controlling chronic skin problems in pets is all very variable and quite complex but we have reams of experience in this field and ultimately with your perseverance we will be able to successfully control the symptoms of the vast vast majority of pets that present to us. For those very few pets that we are unable to treat with success we will offer referral to a specialist veterinary dermatologist such as www.skinvet.ie.
Westie with chronic atopic dermatitis - note the discoloured thickened skin and the hair loss and also the inflammed red ears.
Bichon with atopy affecting feet - note the colour of the hair on the feet. This indicates this dog has itchy feet that he has been chronically licking at.